fix(package): update babylon to version 7.0.0-beta.31 (babel#533)

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "babel-code-frame": "7.0.0-beta.0",
     "babel-traverse": "7.0.0-beta.0",
     "babel-types": "7.0.0-beta.0",
-    "babylon": "7.0.0-beta.22"
+    "babylon": "7.0.0-beta.31"
   },
   "scripts": {
     "test": "npm run lint && npm run test-only",